Automated assay devices such as immunoassay instruments provide multiple reagent containers for executing a plurality of individual assays. Storage space for each reagent container has become a significant aspect of instrument design in that more than one reagent is typically required for each assay. Further, the desire to automate dictates that such instruments operate with minimal operator intervention, thus emphasizing the need for adequate quantities of reagent in each container.
Any solid phase reagent, and in particular one including paramagnetic particles, requires physical agitation for uniform suspension in a liquid medium. Further, other materials such as incompatible liquids (e.g. oil and water) require similar agitation for homogenous distribution. Existing means for accomplishing this agitation include axial rotation of cylindrical containers having mixing fins therein. However, such mechanisms are necessarily complex to implement, difficult to maintain, and each require significant physical space. Further, such containers are not accessible during instrument operation. Seals for such containers are typically provided as a "star cap", or resilient cap having star-shaped slits. Such caps provide an insufficient barrier to long-term evaporation and to spillage when the container is tipped.
In general, the most significant requirements for individual reagent containers and for housings holding such containers include the following. Each container should include multiple compartments such that all reagents required for a single assay are accommodated. A sufficient quantity of reagent(s) should be accommodated within each reagent container for unattended execution of a series of tests, such as 50 to 250 assays, or more. The containers should be arranged within the housing for simple removal and installation, even during instrument operation. Evaporation and spillage of reagents stored within the pack should be avoided by provision of improved sealing means. Finally, efficient and mechanically simple solid particle suspension should be implemented, allowing continued mixing during instrument operation.